Fig. 3. Potential nitrification (black bars), potential denitrification (striped bars), and nitrate removal (white bars) on the surfaces of Eurasian watermilfoil, twigs, sediment, and macro-algae (biofilm area^-1 in A; dry wt.^-1 in B). The samples were collected in Basins B and D (n = 5). Error bars show SD.